Strong coupling theory of phonons in the Hubbard Model

S. Pairault, David Sénéchal, A.–M. S. Tremblay

Satoshi Yamazaki, Shintaro Hoshino, Yoshio Kuramoto

Superconducting transition temperature is studied in the strong-coupling region of the Holstein-Hubbard model that includes both electron-phonon and Coulomb interactions.By combining the dynamical mean field theory with the continuous-time quantum Monte Carlo method, transition temperature is derived numerically.Without Coulomb interaction, our calculation reproduces analytic expressions of the transition temperature for weak and strong coupling limits of electron-phonon interaction.When electron-phonon coupling is strong enough, Coulomb repulsion enhances superconductivity, in contrast to the weak coupling case.The enhancement is due to coherent motion of superconducting pairs that reduce the Coulomb repulsive energy of almost localized electrons.

Anh Tuan Hoang, Toan Thang Nguyen, Ngoc Thuan Nguyen

Zhongbing Huang, Yihong Gao, Werner R. Hanke +1 more

Philipp Werner, Martin Eckstein

We study quenches of the interaction and electron-phonon coupling parameter in the Hubbard-Holstein model, using nonequilibrium dynamical mean field theory. The calculations are based on a generalized Lang-Firsov scheme for time-dependent interactions or externally driven phonons, and an approximate strong-coupling impurity solver. The interaction quench calculations reveal the phonon-assisted decay of excess doublons, while the quenches of the electron-phonon coupling lead to persistent oscillations of the phonons and to a phonon-enhanced doublon production.

Subhadip Nath, N. S. Mondal, Nanda Kumar Ghosh +1 more